The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Manufacturers of compression-ignition engines face increasingly stringent emissions standards, including reductions in allowable levels of nitrides of oxygen (‘NOx’) and particulate matter (‘PM’). Known strategies to reduce emissions include reducing engine-out emissions, and converting engine-out emissions using some form of exhaust gas aftertreatment. Known systems and methods to reduce engine-out emissions include premixing fuel and air in the combustion chamber prior to ignition. Known systems and methods to convert engine-out emissions use some form of exhaust gas aftertreatment device(s), including, e.g., catalytic converters, adsorbers, and afterburners.
Engines using known fuel/air pre-mix charge systems can achieve low NOx and PM emissions at lower engine load operation. However, such operation is limited at higher engine load operation due to excessive combustion noise and combustion stability. Known strategies for fuel/air pre-mix charge systems to expand engine load operation include using multiple fuel injection events during a combustion cycle.